Types of Chemical Weapons
Chemical weapons are classified according to its 'chemical agent'. They are named based on the effects to the human body. A list of the main classes of CWs used in war are listed below. Blistering Agents This agent can burn and blister mainly the skin or any parts of the body coming into its contact. Examples are eyes, mucous membranes and lungs. http://www.fas.org/programs/bio/chemweapons/cwagents.html *Mustard - Sulfur Mustard (HD) and Nitrogen Mustard (HN). Mustards are the most feared vesicant due to its chemical stability and persistency in both cold and temperate climates. By dissolving this agent in non-volatile solvents, its persistency can be increased making it more difficult to be decontaminated. *Phosgene Oxime (CX). CX is white crystalline powder and can decompose spontaneously (has to be stored at low temperatures). The melting point is between 39-40°C and the boiling point is at 129°C. Chemical inactivation using chlorination is effective against mustard and lewisite but ineffective against CX. *Lewisite (L). Colourless and odourless in its pure form, but usually brown with an odour similar to geranium oil. Lewisite is not only a vesicant but also a systemic poison which get absorbed in tissues. British anti-lewisite (BAL) is a dimercaprol functions as the antidote, existing in ointment form. Choking Agents This agent attacks lung tissues and will mainly cause pulmonary oedema. Therefore, they are also classed as lung damaging agents. In extreme cases, the pulmonary oedema is so severe that the lung is filled with liquid and death results from lack of oxygen, giving the effect of choking to the exposed individuals. *Chlorine (CL). Greenish-yellow gas at room temperature; clear, amber-colored liquid under increased pressure or at temperatures below -34°C.http://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750024.html *Phosgene (CG). Colourless gas above 8.2°C; fog-like gas when concentrated; colourless, fuming liquid below 8.2°C; may have the appearance of a white cloud; light yellow liquid when refrigerated or compressed.http://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750023.html *Diphosgene (DP). DP is liquid at room temperature and easier to handle than CG and more persistent than CG and CL. DP is basically CG with chloroform drafted onto it. Both chlorine and phosgene are used in many chemical industrial processes, making the control difficult. Nerve Agents The nerve agents inhibit acetylcholinesterase (AChE) throughout the body. Normally, AChE hydrolyses acetylcholine (ACh) wherever it is released. However, ACh will not be hydrolysed when AChE is inhibited resulting in the accumulation of ACh excessively at its various sites of action.http://www.fas.org/programs/bio/chemweapons/cwagents.html *Tabun (GA). A clear, tasteless liquid with a faint fruity odor which ranges from clear to brown coloured. It can become vapor if heated.http://www.bt.cdc.gov/agent/tabun/basics/facts.asp *Sarin (GB). A clear, colourless, and tasteless liquid that has no odour in its pure form. It can evaporate into vapor.http://www.bt.cdc.gov/agent/sarin/basics/facts.asp *Soman (GD). A clear, colorless, and tasteless liquid with a slight odour similar to camphor containing mothballs or rotten fruit. It can become vapor if heated.http://www.bt.cdc.gov/agent/soman/basics/facts.asp *VX (methylphosphonothioic acid). VX is odourless and tasteless. It is an amber, oily liquid which evaporates as slowly as motor oils.http://www.bt.cdc.gov/agent/vx/basics/facts.asp The "G" agents exist as volatile liquid at room temperature and therefore tend to be non-persistent. Whereas, the "V" agent is relatively non-volatile liquid and therefore is persistent. GB and GD is significantly volatile while GA is less volatile. Blood Agents These agents do not typically affect the blood but do affect the body by being absorbed into the blood. However, normal production of blood components may be interrupted. These agents exert their toxic effects at cellular level by interrupting the electron transport chain in mitochondria.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148621/ The main blood agents are: *Cyanogen Chloride (CK). Colourless liquid below 12.8°C or colourless gas above 12.8°C.http://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750039.html *Hydrogen Cyanide (AC). Colourless or pale blue liquid below 25.6°C or colourless gas above 25.6°C.http://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750038.html Both of these agents are cyanides. Cyanide is a potentially deadly chemical which can exist in various form. However, these two agents exist as colourless gas under normal temperature. Cyanide has a very high affinity for iron. When entering the biological system, it forms complex with trivalent iron of cytochrome oxidase, thus impairing the utilization of oxygen in the tissues which interferes the body's ability to use oxygen. Exposure can be rapidly fatal as it is also a systemic agents whereby it has a whole-body effects, particularly affecting organs most sensitive to low oxygen levels: Central Nervous System (brain), Cardiovascular System (heart and blood vessels) and Pulmonary System (lungs). Riot Control Agents (RCAs) These agents cause temporary disability by irritating the eyes, the skin and the upper respiratory tract. Other names include irritants, lacrimators, harassing agents and most commonly, tear gas.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148621/ RCAs can cause irritation spontaneously when in contact but the effects are usually short-lived. About 15-30 minutes after decontamination or after being away from source, the disability will stop. The irritation caused can be so severe that the victims cannot behave rationally, which will hinder the exposed person's coordination. These 3 chemical agents are of significant importance to RCAs: *Chloroacetophenone (CN) *Chlorobenzylidenemalononitrile (CS) *Dibenzoxazepine (CR) These agents are solid at room temperature and are usually released in the form of aerosols (fine particles). When released to the air, exposure can occur through contact or breathing. RCAs are used by law enforcement officials for crowd control and by individuals and the general public for personal protection (e.g. pepper spray).http://emergency.cdc.gov/agent/riotcontrol/factsheet.asp References Category:Health Category:Chemical Weapons Category:Types